The invention relates to tools for folding an edge of a molded or laminated panel for forming a panel rim, and cutting or trimming excess material from the rim. The tool is particularly suitable for use during the molding and laminating process for fabricating interior trim components for motor vehicles.
Interior trim panels for motor vehicles and the like are typically fabricated by laminating and molding a cover sheet material, such as a fabric, vinyl, imitation leather, or the like onto a supporting substrate, such as a substrate of plastic, synthetic composite, or a hybrid composite including natural materials as well as synthetic materials. Generally, the cover sheet and the substrate are thermo-formable, i.e. may be heated to a softening or molding temperature, are then molded into a desired contoured shape, and then rigidify to maintain the contoured shape upon cooling.
Due to tolerances and misalignments that arise during the molding and laminating process, and due to the stretching and molding deformation to which the cover sheet and the substrate are subjected, the cover sheet must typically be initially provided with oversized dimensions relative to the finished size of the resulting laminated panel. For this reason, it is necessary to cut or trim the excess cover sheet material along the edges of the cover sheet after the laminated and molded panel has been completed. Various apparatus and methods are known for automatically or semiautomatically carrying out such cutting or trimming of the excess cover sheet material along the edges of a molded panel. For example, see U.S. Pat. Nos. 5,076,880; 4,923,539; 4,519,766 and 4,471,679 in this regard.
Generally, a stamping knife or cutting blade is carried by a tool holder which in turn is actuated by a piston cylinder device or the like. The piston cylinder device is actuated to press the cutting blade against the excess cover sheet material along an intended trimming line, in order to thereby stamp-cut the cover sheet material along this intended trimming line. The cutting blade may cooperate with a stamp cutting counter surface or anvil surface on the opposite side of the cover sheet material, in order to carry out the stamp cutting.
Even after the excess cover sheet material has been cut away around the edge or rim of the substrate and the finished laminated panel, there has been a demand for a higher quality finish at the edge or rim of the panel. Namely, the cut edge of the cover sheet is subject to fraying or delamination or the like if it is left exposed directly at the edge or rim of the panel, and in any event is not visually attractive if it can be seen from the decorative front side of the finished panel.
For these reasons, it has become known to fold the edge of the cover sheet material back around a rim of the substrate, or to fold back the cover sheet and the substrate together to form a rim of the panel. In this manner, the actual edge of the cover sheet is hidden and protected against fraying or delamination, because it is folded and laminated around the rim of the substrate onto a back surface thereof. In this context, please see U.S. Pat. Nos. 5,718,791 and 5,324,384.
According to the general conventional practice and knowledge in the art, the cover sheet edge may be edge-folded by at least 90xc2x0 around the panel rim, or the cover sheet and substrate may be folded back together by at least 90xc2x0, in order to cover and thereby hide the edge of the cover sheet. Once the finished panel is installed in the interior of a motor vehicle or the like, the rim of the panel will be securely held against other components of the motor vehicle, so that the back-folded edge of the cover sheet will be completely hidden and enclosed. The 90xc2x0 edge-folding process can be carried out in substantially one working operation, or an immediate succession of steps in a single molding apparatus, whereby the cover sheet material and the substrate are laminated together, molded into the intended contoured shape, and then edge-folded to form the panel rim.
While the prior art has provided the edge cutting or trimming methods and apparatus as described above, as well as the edge-folding methods and apparatus as described above, the prior art has not provided a satisfactory manner of combining the edge-cutting and the edge-folding. Namely, after a cover sheet edge (either with or without the substrate) has been edge-folded back to form the panel rim as described above, there still exists an excess margin of cover sheet material along the edge of the cover sheet that has been folded back around the panel rim.
Thus, after the molded, laminated and edge-folded panel has been substantially completed, the excess margin material must be trimmed off in a subsequent manual or mechanical step. This requires considerable extra effort, even if the edge-trimming is carried out mechanically using a suitable stamp-cutting tool. Particularly, it is considerably difficult to properly align the molded and laminated panel in a mechanical cutting or trimming station and then to secure the panel into exactly the correct registered position so that the cutting blade or blades will accurately trim off the excess margin material along the intended trimming line. Even with great care being exercised in this step, unavoidable misalignment of the panel, and particularly the edge-folded rim thereof, relative to the cutting tool results in miscutting of some panels which must then be rejected and scrapped. The additional effort and steps required for carrying out the edge-cutting after the edge-folding also slow down the throughput of a panel forming apparatus, which in turn increases the cost of production. Furthermore, the provision of separate edge-folding and edge-cutting tools or work stations significantly increases the size, complexity and cost of the overall panel manufacturing apparatus.
Attempts have been made to combine an edge-folding plunger with a cutting blade in order to carry out the edge-folding and the edge-cutting in a single operation. However, such attempts have suffered substantial difficulties. For example, if the cutting blade is rigidly fixed to the edge-folding tool or plunger so as to form a single integral unit thereof, unsatisfactory results are obtained. During the pre-forming or molding process, the cover sheet and the substrate material are stretched, deformed, and placed under tension. If an edge-cutting blade and the edge-folding plunger are rigidly integrated into a single unit, as this integrated unit is pressed against the cover sheet edge to carry out the edge-folding and edge-cutting, the cutting blade will cut into the cover sheet material, which is under tension, as the edge-folding and molding process is carried out. The cutting blade will penetrate entirely through the tensioned material and cut it off in its tensioned state before the edge-folding process has been completed, i.e. before the edge-folding plunger has completely pressed the cover sheet and substrate material layers into their finished edge-folded condition. For this reason, the cover sheet would always be cut shorter than the substrate, since the cutting blade cuts through the cover sheet while it is under tension during or even before the edge-folding process has been carried out. When the integrated tool is retracted, the cover sheet, which was cut under tension, will have a tendency to shrink back, whereby the cut edge of the cover sheet might even shrink around the folded-back edge or rim of the substrate and be physically exposed at that location.
In view of the above, it is an object of the invention to provide an integrated or combined tool that can carry out edge-folding and edge-cutting of a panel rim of a laminated panel in substantially a single operation and a single work station. It is a further object of the invention to provide such a tool that can achieve a high quality edge-folded and trimmed panel rim of a laminated panel with a very simple and economical structure and operation. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in a combination tool for edge-folding and cutting a panel rim, wherein the tool comprises a tool holder frame, a cutting and compressing blade rigidly secured to the tool holder frame and an edge-folding tool or plunger that is movably connected to or arranged in the tool holder frame. Thereby, the edge-folding tool is slidably movable relative to the cutting and compressing blade. Preferably, the edge-folding tool is biased by a biasing device to protrude outwardly away from the tool holder frame, for example by a compression spring, a stack of cupped disk springs, a repulsion magnet arrangement, a hydraulic or pneumatic piston-cylinder device, elastomeric members, or the like. The edge-folding tool can be pressed against the biasing force, for example the spring force, to be slidingly retracted into the tool holder frame while moving parallel to and sliding directly along the longitudinal extension of the cutting and compressing blade. A receiving chamber or hollow space within the tool holder frame receives the edge-folding tool as it is retracted, and provides a parallel sliding guidance for the edge-folding tool. In a neutral starting position, the working face or stamping face of the edge-folding tool protrudes forwardly from the tool holder frame to a greater extent or beyond the cutting edge of the cutting and compressing blade.
With the above construction, the inventive tool operates as follows. In a prior molding and laminating operation, a cover sheet has been laminated onto a substrate, the cover sheet and substrate together have been compressed and molded between an upper form and a lower form, and a clamping slip frame or tentering frame has pulled the excess margin of the cover sheet and the substrate beyond the area at which an edge-folded rim is to be formed. Then, the present inventive tool is moved from its initial position toward the rim area of the cover sheet and substrate. As the tool, and particularly the tool holder frame is moved forward in a linear stamping direction, the stamping face of the edge-folding tool first contacts the excess margin of the cover sheet and substrate materials, and compresses these materials against the lower mold. At this point, the cutting and compressing blade has not yet contacted the cover sheet and the substrate.
As the tool holder frame is moved further in the linear stamping direction, after the edge-folding tool has compressed the margin area of the cover sheet and the substrate, the edge-folding tool will progressively be pushed into the tool holder frame against the biasing spring force. Then, the cutting edge of the cutting and compressing blade touches and penetrates into the cover sheet and the substrate, while the stamping face of the edge-folding tool remains pressed against the cover sheet and substrate.
Preferably, the linear stamping direction is oriented at an acute angle relative to the 90xc2x0 edge fold or rim to be formed, and the cutting edge of the cutting and compressing blade is tapered at the same angle. Thereby, the tapered compressing face of the blade compresses the rim of the panel as the cutting edge penetrates through the cover sheet and the substrate against the cutting counter surface to complete the cut.
Advantageously according to the invention, the edge-folding tool has completely folded and compressed the cover sheet and the substrate against the corresponding mold surfaces of the lower mold before the cutting blade cuts into and through the cover sheet and the substrate. Although the edge-folding tool and the cutting blade are integrated into a single combined tool that carries out a single linear stamping motion, the edge-folding and stamping tool carries out its work before the cutting blade.
Thereby, the present invention avoids the above described undesirable cutting of the cover sheet while it is being deformed, compressed, and tensioned by the edge-folding stamp.